1. Field of the Invention
The present invention relates to an image reading apparatus such as a scanner for reading an original on which images are recorded.
2. Related Background Art
An illumination apparatus of a conventional image reading apparatus such as a scanner has been designed to equalize the intensities of light from both the upstream and downstream sides of an original (5:5 illumination) in order to erase shades to be caused by an original illumination direction when a patched original is read.
FIG. 13 illustrates the principle of illumination. An original 201 has a patched original 202 pasted thereon. This original 201 is placed on a glass mount 203 and illuminated with two illumination units 204 and 205 from a lower position along opposite directions. In this case, although illumination with the illumination unit 205 does not produce a shade on the right side of the patched original, illumination with the illumination unit 204 produces a shade 206 on the original 201 because of the presence of the patched original 202.
To avoid this, a highlight area of an image has been conventionally set rather dark by image processing or the like to erase shades from the image, or in a copier machine, the highlight area of an image has been conventionally set rather dark by an image forming process to erase shades.
However, recently, user requirements for the reproduction of a highlight area with an image reading apparatus are becoming severe, and even the highlight area is desired to be reproduced with fidelity. However, if an apparatus is designed to reproduce even the highlight area, shades are produced when a patched original or the like is read. With conventional techniques, the reproduction of highlight areas and the erasure of shades are contradictory with each other.
An image forming apparatus is prevailing which reads an image of an original with an optical sensor and the read image of the original is subjected to various image processing to record it on a recording sheet. However, although a conventional image forming apparatus can optically read color information recorded on an original, it cannot read an original with an irregularly raised pattern such as points of braille characters in monochrome color.
It is an object of the present invention to provide an image reading apparatus capable of satisfying both the reproduction of highlight areas and the erasure of shades.
It is another object of the present invention to provide an apparatus capable of reading irregularly raised pattern information.
According to one embodiment of the invention, an image reading apparatus capable of satisfying both the reproduction of highlight areas and the erasure of shades is provided which comprises illuminating means for illuminating an original recorded with an image along a plurality of directions, reading means for optically reading the illuminated original, and controlling means for controlling to the reading means to read the original a plurality of times and controlling the illuminating means in accordance with a sequential number of a reading order.
According to another embodiment of the invention, an irregularly raised pattern reading apparatus is provided which comprises a sheet member placed on an original recording with an irregularly raised pattern and made of a flexible material, and signal generating means for generating an electrical signal corresponding to the irregularly raised pattern reflected upon a surface of the sheet member.
By placing the sheet member on an original recorded with the irregularly raised pattern such as braille characters and three-dimensional lines, it is possible to read the irregularly raised pattern and obtain electrical signals corresponding to the irregularly raised pattern.
According to another embodiment of the invention, an irregularly raised pattern reading apparatus is provided which comprises switch means including a plurality of switches mounted on a surface in contact with an original recorded with an irregularly raised pattern and operated in response to the irregularly raised pattern on the original, the switch means generating an electrical signal in accordance with a state of each of the plurality of switches.
Since a plurality of switches is selectively turned on or off in accordance with the irregularly raised pattern, electrical signals corresponding to the irregularly raised pattern can be obtained.